Illuminating device



Dec. 30, 1941. M. c. HARLEY ILLUMINA'IING DEVICE 5 sheets-sheet 1 Filed June 22, 1958 n/ e M Na 1 QM .flI m Dec. 30, 1941. M. c. HARLEY 2,267,974

ILLUMINATING DEVICE Filed June 22, 1938 s Sheets-Sheet 2 '777. C. jiZzrZey 1772/67? for Dec. 30, 1941- Q M. c. HARLEY 2,267,974

ILLUMINATING DEVICE Filed June 22, 1938 3 Sheets-Sheet 5 2 6. Early .Zn Venfa Patented Dec. 30, 1941 ILLUMINATING DEVICE Maldon Cavendish Harley, Harlington, Hayes,

England Application June 22, 1938, Serial No. 215,264 In Great Britain June 23, 1937 i 4 Claims.

This invention relates to illuminating devices, more especially of the projecting lamp type for aircraft, its general objects being an improved arrangement of retractable lamp and means of moving such a lamp between operative position and a concealed position within an aerofoil or other body.

The invention generally consists in a retractable lamp having a pivotal action into and out of an aerofoil or other chamber preferably. about an axis both offset in relation to the aerofoil surface and external to the peripheral limits of the lamp body.

The invention also consists in a lamp as indicated operated by crank and lever or other equivalent means co-operating to perform the desired angular lamp movements and preferably also to provide stops for locking the lamp in either extreme of its angular movement.

The invention also consists in 'a lamp as indicated comprising slipping clutch means included in the drive for angularly moving the lamp.

The invention also consists in a lamp as indicated having associated therewith a power source for the angular movement of the lamp.

The invention also consists in a retractable lamp arranged for accommodation with suitable operating means in an aerofoil of minimal thickness.

The invention also consists in a retractable aircraft lamp substantially as hereinafter indicated.

Referring now to the accompanying drawings:

Figure 1 is a part sectional elevation of a con- 'struction of aircraft lamp according to the present invention, the section being taken in a plane substantially parallel to the line of flight of the aircraft,

Figure 2 is an elevation looking rearwards,

Figure 3 is a plan showing essential parts of the same construction, and

Figure 4 is a fragmentary plan of a modified drive.

In carrying the invention into effect in one form by way of example as shown in Figures 1, 2 and 3, the general construction of lamp is apparent from the drawings, a being the front face at which suitable front glass and lens means are arranged, a being the rear part of the reflector, a being a flange bordering the lamp ring 11 received by a flange a when the lamp is fully retracted, so that the face a then lies flush with the aerofoil surface 0..

The pivoting arrangement is such as to permit the lamp body to be received into and swivel freely out of a chamber 0 of minimal diameter constituted by a ring 0 and case 0 the section of which ring is practically uniform in all radial planes and which is adapted to receive the front ring at of the lamp wholly from the outside. To permit of this the pivotal axis (to be understood to lie transversely of the line of flight indicated by arrow 3:) is located a short distance 11 in front of the chamber and some distance 2 inwards of, i. e. offset from the lamp receiving end of said chamber, at the aerofoil surface a with which the lamp front lies flush when the lamp is fully retracted. The axis or hinge pin e is borne inbearings e 6 preferably cast integrally with thephousing ring as also is a Web I (or platform) referred to hereinafter.

The mounting and swivelling is effected by means concealed in 'the aerofoil: such means 7 comprises an'arm d conveniently integral with the main body (e. g. front ring part 11) of the lamp proper, which arm radiates outwardly in a swan-neck curve clear of the hinge pin referred to through a short distance, it then having a quadrantal portion d centrally borne by the hinge pin between the bearings referred to. Beyond this and outside of the lamp housing or chamber the arm continues as a more or less parallel member extending in a plane parallel with the lamp front and slotted at d along its length. In the slot is received a crank pin g carried by a crank disc 9 also supported for rotation by'bearing means e fixed in relation to the chamber c, the rotation of the disc, effected by means hereinafter described, being imparted through the sliding surfaces of the crank pin and co-operating slot, as the requisite angular movement of the arm d to operate the lamp; such movement being one of more or less according to the degree required. The quadrantal portion d referred to penetrates a complementary shaped opening 0 through the side wall of the case and/or chamber parts 0 but forms therewith in all positions a closure excluding foreign matter from the operating mechanism irrespective of the angular position of the lamp.

By a correct proportioning of the dimensions and space relation of the co-operating parts, e. g. the radius of the crank pin from the centre of the disc and the pitch of the pivots, a crankpin movement of say 270 from the dotted position 9" round anticlockwise to the dotted position g is so correlated to the 90 movement of the lamp as to bring the pin hard up into abutment with the inner end 12 of the slot d when the lamp having moved from the mid-position in which it is shown in Figure 1 has reached either the full out or the fully retracted position whereby to lock the lamp positively and rigidly in these extreme positions. The locking thus obtained is an effective one as the drawings show for it occurs each time when the arm is in an angular position such that it can exert no back turning moment on the driving pin tending to cause or permit displacement of the lamp or to load the driving disc and cables etc. beyond it.

The drive to the crank disc may comprise a pulley h peripherally formed to take a cable 1' which is moved to and fro by hand or otherwise from, say, the cockpit of the aircraft. The pulley may be serrated for the modern cable drive shown. Other convenient drives may be incorporated, including pinion gearing if desired. Any I such drive preferably incorporates a spring loaded or other friction clutch, sufficiently positive in its transmission to deal with the weight of the-lamp and/or the force of wind pressure upon it when moved out of the aerofoil. A drive of such kind prevents damage to the parts and obviates the need for an exact or critical displacement of the remote or other operating means to move the lamp fully over to extreme positions which are conveniently determined by the stop means described.

A convenient and preferable drive illustrated by Figure 4 is by means of a fractional horsepower electric motor 1c and. reducing gear 10 mounted upon a platform modification ,f of the web mentioned above, the drive from the reducing gear being conveniently via pinion wheel k to a hard fibre (e. g. Tufnal) spur wheel h which constitutes one element of a friction clutch operating as above, the other elements being the crank disc g itself, and a disc 9 resiliently gripped about the member h by spring means I on generally well-known principles.

The operating armfpivots, crank disc and associated gears and motor when provided are all proportioned in size and positioned so as to constitute a compact arrangement, e. g. whereby they may be contained within the aerofoil surface and a plane parallel thereto at a minimal distance within the aerofoil to accommodate the lamp. chamber. In this way a compact mechanism provided which is readily accommodated in any aerofoil, e. g. wing, of suflicient depth mergers, receive the retracted lamp.

retractable lamps as above, 'orindeed in any retractable lampwherein the filamen'tlead pinch of the bulb lies more or less: above the filamentover the greater or any other part of the angular'movement, there are frequent failures due to overheating. It is desirable therefore to avoid switching on the lamp in such positions and it is a feature, of this invention that the angular'posit'ion of the lamp may itself determinewhetheror not itcan be lit. Conveniently the operating cable orequivalent member angularly moving the lamp may include or carry with it in its movement means for opening or closing an electric switch included in the lighting circuit. It may be so arranged that the circuit remains open until the lamp has been moved out of its housing by say 30-40", after which the circuit is closed and under the sole control of the usual dashboard switch until the lamp is retracted to, for instance, the same angular position. If the operating means comprises a handle by rotating which a Bowden or other transmission. may be caused to'operate the, lamp,

the handle may have movable with it a screwed spindle caused to advance and retract a nut or equivalent which makes and breaks electric contacts at various regions of its travel either directly or indirectly. Preferably some adjustment is provided so that the control may be effective over any desired angle of movement of the lamp. A mercury switch, in which the contact-making member is a quantity of mercury, may be used to efiect the above action, and may be attached if desired directly to the lamp.

One specific form and arrangement of switch embodied in the foregoing figures of the drawings comprises a composite plunger reciprocatable in a chamber 111. mounted at the front of the member 1, which plunger moves under the action of an internal spring n so that the latter ordinarily holds together metallic contacts 0 o in circuit with one of the electric leads p (e. g. the lead common to the various bulb filaments). This position of the plunger is. permitted by providing a negative or a recessive cam surface q at the periphery of the crank disc g The surface q extends over those parts of the disc which run past the plunger during the latter part, say about 5060 of the angular movement, of the lamp out of its housing; the plunger is. depressed into its chamber and contact broken when it meets and rides upon the raised or normal periphery q of the disc during the first part of said movement, i. e. some 30-40". The chamber 171. is of insulating material and the composite plunger which is slidable in its bore comprises a forward portion 1' of Tufnal or like fibrous material stemmed into a brass or other metal portion r v having a shank passing out through the end of the chamber m and forming one of the contacts to which the electrical connection is made. The stem r passes slidably through a brass or like annulus conveniently sprung into position in the bore and providing the other contact which, having an outside connection to it, is engaged by the face of the member 0. under the action of the spring to complete the circuit; and separated to break it.

I claim:

1. In a retractable lamp assembly, a lamp, means providing a chamber for receiving said lamp, a pivotal connection between said lamp and said means about which the lamp is angularly movable between an extreme retracted position within said chamber and an extreme extended position outside the chamber, driving means for moving said lamp comprising an arm movable with said lamp about said pivot and having a slot therein extending radially in relation to said pivot, rotatable means adapted to turn about an axis offset with respect to said pivot, a pin carried by said rotatable means engaging said arm within said slot to angularly move the arm and the lamp upon rotation of said rotatable means, said slot terminating to provide a single abutment radially displaced from said pivot and so located in relation to the radial displacement of the pin from the axis of the rotatable means and to the offset between the axis of the rotatable means and the pivot whereby the abutment obstructs further movement of said pin in one direction at both angular extreme positions of said arm, said pin and abutment being arranged in such a manner that at both extreme positions of said arm no turningmovement is transmitted to therotatable means, said pivotal connection being arranged in a position inwardly offset with respect to the lamp receivrantal portion extending through an opening in the means providing said chamber.

2. In a retractable lamp assembly, a lamp, means providing a chamber for receiving said lamp, a pivotal connection between said lamp 7 and said means about which the lamp is angularly movable between an extreme retracted position within said chamber and an extreme extended position outside the chamber, driving means for moving said lamp comprising an arm movable with said lamp about said pivot and having a slot therein extending radially in relation to said pivot, rotatable means adapted to turn about an axis offset with respect to said pivot, a pin carried by said rotatable means engaging said arm within said slot to angularly move the arm and the lamp upon rotation of said rotatable means, said slot terminating to provide a single abutment radially displaced from said pivot and so located in relation to the radial displacement of the pin from the axis of the rotatable means and to the offset between the axis of the rotatable means and the pivot whereby the abutment obstructs further movement of said pin in one direction at both angular extreme positions of said arm, and said pin and abutment being arranged in such a manner that at both extreme positions of said arm no turning movement is transmitted to the rotatable means.

3. In a retractable lamp assembly, a lamp, recess-defining means for accommodation of said lamp, a pivotal connection between said lamp and said means and about the axis of which the lamp is angularly movable between an extreme retracted position inside said means and an extreme extended position outside said means, driving means for effecting said angular movements comprising a member movable with said lamp about said connection axis and provided with a track extending from the connection axis, rotatable means engaging slidably within said track and reversibly rotatable about another axis, a slipping clutch device for driving said rotatable means so as to efiect said angular movements of said member and said lamp, and a single abutment on said member limiting said angular movements at both the extreme extended position and the extreme retracted position of said lamp, said parts being so dimensioned and spaced that they cooperate in such a manner that in one direction of the drive the clutch slips when the reversibly rotatable means is arrested by the abutment and the lamp is in its fully extended position and in the reverse direction of the drive when the lamp is fully retracted while in both extreme positions the member movable with the lamp cannot transmit a turning moment to the reversibly rotatable means.

4. In a retractable lamp assembly, a lamp, re-

cess-defining means for accommodation of said lamp, a pivotal connection between said lamp and said means and about the axis of which the lamp is angularly movable between an extreme retracted position inside said means and an extreme extended position outside said means, driving means for efiecting said angular movements comprising an arm integrally movable with said lamp angularly about said connection axis and provided with a slot extending radially in relation to said pivotal axis, means rotatable about an axis ofiset from said pivotal axis and carrying a pin engaging slidably in said arm slot, a slipping clutch device driving said rotatable means, a single abutment on said arm, said parts being so dimensioned and spaced that they 00- operate in such a manner that in one direction of the drive the clutch slips when the pin on the rotatable means is arrested by the abutment and the lamp is in its fully extended position and in the reverse direction of the drive when the lamp is fully retracted while in both extreme positions the arm cannot transmit a turning moment to the reversibly rotatable member.

MALDON CAVENDISI-I HARLEY. 

